FIG. 38 is a sectional view of an example of a proximity sensor. The proximity sensor 900 shown in the figure includes a glass-epoxy substrate 91, a light-emitting element 92, a light-receiving element 93, primary mold resin portions 94, 95, and a secondary mold resin portion 96. The light-emitting element 92 and the light-receiving element 93 are mounted on the glass-epoxy substrate 91. The light-emitting element 92 emits infrared light. The light-receiving element 93 sends out an electric signal corresponding to the amount of received infrared light. The primary mold resin portions 94 and 95 are transparent and transmit infrared light. The primary mold resin portion 94 covers the light-receiving element 93 on the glass-epoxy substrate 91. The primary mold resin portion 94 has a convex light-incident surface 940. The primary mold resin portion 95 covers the light-emitting element 92 on the glass-epoxy substrate 91. The primary mold resin portion 95 has a convex light-emitting surface 950. The secondary mold resin portion 96 is black and does not transmit infrared light. The secondary mold resin portion 96 covers the primary molding resin portions 94 and 95 on the glass-epoxy substrate 91. The secondary mold resin portion 96 has a first opening 961 and a second opening 962. The light-incident surface 940 is exposed to the direction z side through the first opening 961. The light-emitting surface 950 is exposed to the direction z side through the second opening 962. The highest point of the light-incident surface 940 is at the same position as the edge of the first opening 961 in the direction z. Similarly, the highest point of the light-emitting surface 950 is at the same position as the edge of the second opening 962 in the direction z. This type of proximity sensor is disclosed in e.g. Patent Document 1.
For instance, the proximity sensor 900 is incorporated in a touch panel type electronic device (such as a cell phone). The proximity sensor 900 is arranged adjacent to a liquid crystal display 902 of an electronic device. The proximity sensor 900 and the liquid crystal display 902 face a light-transmitting cover 903. The infrared light L91 emitted from the light-emitting element 92 travels through the light-emitting surface 950 toward the light-transmitting cover 903. The infrared light L91 then passes through the light-transmitting cover 903 to be reflected by the object 901. The infrared light L91 reflected by the object 901 passes through the light-transmitting cover 903 again. Then, the infrared light L91 passes through the light-incident surface 940 to be received by the light-receiving element 93. The light-receiving element 93 sends an electric signal corresponding to the amount of the received infrared light to a controller (not shown). When the output level from the light-receiving element 93 exceeds a predetermined threshold, the controller determines that the object 901 is close to the liquid crystal display 902. That is, in an electronic device, when a user holds a liquid crystal display 902 close to his or her cheek to make a phone call, the approach of the cheek is detected by the proximity sensor 900. By this, the touch panel operation using the liquid crystal display 902 is disabled during a phone call, whereby malfunction during a phone call is prevented. Also, during a phone call, the liquid crystal display 902 is set to an “off” state, which suppresses power consumption of the battery of the electronic device.
As shown in FIG. 38, the proximity sensor 900 is arranged to have a certain distance from the light-transmitting cover 903. Thus, some part of the infrared light emitted from the light-emitting surface 950 impinges on the light-transmitting cover 903 with a relatively large incident angle. The light impinging on the light-transmitting cover 903 with a relatively large incident angle is reflected by the light-transmitting cover 903 to become noise light L92. The noise light L92 impinging on the light-incident surface 940 can be received by the light-receiving element 93. When the noise light L92 is received by the light-receiving element 93, false detection may occur in which the controller determines the object 901 is close to the light-transmitting cover 903, though the object 901 is not actually close to the light-transmitting cover.
The proximity sensor 900 may include an illuminance sensor, in addition to the light-receiving element 93. Each of the illuminance sensor and the light-receiving element 93 is made of a chip and arranged on the glass-epoxy substrate 91. In recent years, there is an increasing demand for size reduction of such a proximity sensor 900.
In the proximity sensor 900, between the primary mold resin portion 94 and the primary mold resin portion 95, the same transparent resin as the material for the primary mold resin portions 94, 95 may be formed in the space between the secondary mold resin portion 96 and the glass-epoxy substrate 91. In this case, during the use of the proximity sensor 900, the light emitted from the light-emitting element 92 may pass through this transparent resin to be received by the light-receiving element 93. The above-described false detection may occur when the light emitted from the light-emitting element 92 passes through this transparent resin and received by the light-receiving element 93.